CORR Insights®: Does Minimally Invasive Surgery Provide Better Clinical or Radiographic Outcomes Than Open Surgery in the Treatment of Hallux Valgus Deformity? A Systematic Review and Meta-analysis

Where Are We Now?

Hallux valgus is stated to be the most common foot deformity; it affects 23% to 35% of the general population [8]. More than 150 different surgical procedures have been described to treat hallux valgus [9], and lately, procedures described as “minimally invasive surgery” (MIS) are seeing wider use. These typically involve an incision of 3 to 5 mm [4] or a 1-cm medial incision [3]. In both minimally invasive techniques, a 2-mm burr or oscillating saw is used for osteotomies to correct a deformity. Appropriate fixation (screws or K-wires) is used as indicated based on the severity of the deformity being addressed. Proponents have suggested that MIS techniques may decrease stiffness and reduce postoperative morbidity; it’s clear enough that the scars are shorter, but whether the other purported benefits of these approaches are perceptible to patients remains controversial.

That being so, it’s logical to ask how surgical procedures meant to address a painful deformity using very small incisions compare with those performed through traditional approaches with respect to patient-reported outcomes, pain, radiologic outcomes, complications, and duration of surgery.

Alimy et al. [1] performed a meta-analysis of available randomized controlled trials and prospective controlled studies. The authors found no clinically important benefits in terms of outcome scores or radiographic findings associated with the use of MIS techniques. They added that the methodologic shortcomings of many of the source studies likely inflated the apparent benefits of MIS approaches, such that they may not even be as good as traditional approaches. Based on the discoveries in this well-done meta-analysis, surgeons should question whether there really are any clinically important benefits of MIS compared with traditional approaches for patients with hallux valgus. Even a meta-analysis such as this is likely underpowered to comment on uncommon harms and complications, and so that question probably remains unanswered. In light of that, it seems reasonable to offer MIS if the surgeon is facile with it and the deformity in question seems easy to correct, but we should have a low threshold to offer more-traditional and well-tested alternatives in other situations.

Where Do We Need To Go?

There could be benefits to MIS, even though this meta-analysis [1] found that hallux valgus treated with MIS did not result in improved clinical or radiologic outcomes compared with open surgery. The use of MIS must be weighed against the tried-and-true surgical interventions performed for hallux valgus. Robust evidence is needed to determine whether MIS improves radiologic and clinical outcomes [5].

The authors [1] correctly stated there were differences among the surgical approaches compared—several different techniques were included—and that more than one procedure may be used to treat the bone and soft tissues involved in a patient’s deformity. Continued collection of data is beneficial. In the future, similar surgical techniques could be compared. The study duration was also a limitation, and longer studies are needed, because a longer duration may detect potential harms such as recurrence, nonunions, and implant failure.

Functional outcome was evaluated with the American Orthopaedic Foot and Ankle Society score. This is not a validated outcome measure [7]. Subsequent studies have demonstrated its limitations, including insufficient reliability and validity [2]. The American Orthopaedic Foot and Ankle Society has endorsed validated patient-reported outcome instruments such as the Patient-Reported Outcomes Measurement Information System (PROMIS) to assess a patient’s general health and functional status, as well as treatment outcomes, in any of its domains (physical, mental, and social health) [2]. Future randomized trials should seek to use these instruments. Until or unless high-quality randomized trials show benefits large enough for patients to perceive, ideally using validated outcomes tools like the PROMIS, surgeons should not claim these MIS approaches deliver more than they seem to.

How Do We Get There?

The findings of this meta-analysis [1] put the ball back into the court of those who believe MIS approaches have benefits. To support a recommendation of wide adoption of these approaches, a new round of randomized trials would be needed; these trials should seek to compare similar osteotomies performed through different surgical approaches, stratify by sex and gender, and use validated outcomes tools like the PROMIS. The use of validated and reliable patient-reported outcome measures will quantify patients’ perceptions of health, function, and quality of life associated with this surgical intervention [2, 6]. Lastly, the surgeon’s role and experience depend on the learning curve for MIS. The surgical decision to use MIS requires an appropriate evaluation of the deformity’s severity, thickness of the soft tissue envelope, fragility of the skin, and vascular status. But unless future studies demonstrate real benefits to these approaches that patients can perceive, time-tested surgical approaches should be used. Claims about MIS must have specific clinical outcomes that can improve patient care and functional results [5].